Fail-safe liquid oxygen to gaseous oxygen conversion system

ABSTRACT

A fail-safe system for supplying oxygen to a breathing regulator operated upon demand by a recipient. A liquid oxygen storage vessel has an outlet port connected to its inlet port through a build-up circuit. As the liquid oxygen flows through the build-up circuit it is converted from a liquid to a gas through the effect of thermal energy. As a result of the liquid to gas conversion, a high internal pressure is created in the build-up circuit. A pressure responsive member placed in the build-up circuit will interrupt the flow when the pressure reaches a predetermined value during the active operation of the system. A supply circuit connected to the build-up circuit transmits the oxygen as a gas to operate the breathing regulator. A first solenoid in response to an electrical signal controls a flow control valve connected in the build-up circuit. An operational switch on the panel regulator supplies the electrical signal to the first solenoid, opening the control valve. As the valve opens, a latching shaft controlled by a second solenoid engages a notch on the plunger of the flow control valve to hold the valve open. The flow control valve will remain open until an operational closing signal is communicated to the second solenoid. Upon receiving the signal, the second solenoid moves the latching shaft away from the notch permitting a resilient member to close the fluid flow outlet port to the build-up circuit. To prevent excessive pressure in the build-up circuit when the first solenoid closes the flow control valve, a by-pass valve is utilized to provide an escape to the atmosphere.

United States Patent Cramer [151 3,707,078 [451 Dec.26, 1972 [54]FAIL-SAFE LIQUID OXYGEN TO GASEOUS OXYGEN CONVERSION SYSTEM [72]Inventor:

[73] Assignee: The Bendix Corporation 22 Filed: Feb. 10, 1971 [21] Appl.No.: 114,313

Robert L. Crlmer, Davenport, Iowa Primary Examiner-Meyer PerlinAssistant Examiner Ronald C. Capossela Attorney-William N. Antonis andPlante, Hartz, Smith & Thompson [57] I ABSTRACT A fail-safe system forsupplying oxygen to a breathing regulator operated upon demand by arecipient. A liquid oxygen storage vessel has an outlet'port con.-nected to its inlet port through a build-up circuit. As the liquidoxygen flows through the build-up circuit it is converted from a liquidto a gas through the effect of thermal energy. As a result of the liquidto gas conversion, a high internal pressure is created in the build-upcircuit. A pressure responsive member placed in the build-up circuitwill interrupt the flow when the pressure reaches a predetermined valueduring the active operation of the system. A supply circuit connected tothe build-up circuit transmits the oxygen as a gas to operate thebreathing regulator. A first solenoid in response to an electricalsignal controls a flow control valve connected in the build-up circuit.An operational switch on the panel regulator supplies the electricalsignal to the first solenoid, opening the control valve. As the valveopens, a latching shaft controlled by a second solenoid engages a notchon the plunger of the flow control valve to hold the valve open. Theflow control valve will remain open until an operational closing signalis communicated to the second solenoid. Upon receiving the signal, thesecond solenoid moves the latching shaft away from the notch permittinga resilient member to close the fluid flow outlet port to the build-upcircuit. To prevent excessive pressure in the build-up circuit when thefirst solenoid closes the flow control valve, a by-pass valve isutilized to provide an escape to the atmosphere.

IIIIIII ,n

FAIL-SAFE LIQUID OXYGEN TO GASEOUS OXYGEN CONVERSION SYSTEM BACKGROUNDOF THE INVENTION Presently known liquid oxygen. to gaseous oxygensystems have a pressure opening and closing valve whereby gas is drawnfrom the top of the storage container when the system pressure reaches apredetermined range of pressures. Pressure above this predeterminedrange is allowed to escape through a relief valve. Liquid oxygen trappedin the supply line during nonuse is prevented from returning to thestorage chamber by a check valve located between the pressure openingvalve and the pressure closing valve. However, as this trapped liquid isconverted to gas due to the thermal energy resulting in an increase inpressure in the system, pressurized gas above a predetermined value islost through a relief valve. As the pressure in the system drops thepressure opening valve, permits. fluid flow into the supply line tomaintain an operating pressure at all times. Devices have been designedto prevent the pressure opening valve from operating, but require theoperator to manually inactivate the pressure opening valve. If theoperator inadvertently failed to engage this device, the oxygen supplywould cycle to maintain the operating pressure with a resulting loss ofoxygen as gas through the relief valve.

SUMMARY or THE INVENTION To reduce the loss of the oxygen during thestored or passive period, I have invented a liquid to gaseous oxygenconversion system having a flow control valve that is responsive to theON-OFF toggle of a demand breathing regulator. The flow control valve isneither normally opened nor closed, but will remain in its intendedposition until an overt act on the part of the operator sends a signalindicating a desired change.

To obtain low boil-off in the liquid to gaseous oxygen conversionsystem, the toggle of the regulator is placed in the OFF position. Thetoggle will remain in the OFF position until opened by the operator. Afirst solenoid of the flow control valve has an internal plungerresiliently biased toward an outlet port controlling flow through thebuild-up circuit. When the toggle is manually switched by an operator tothe ON position, an electrical impulse is transmitted to energize thefirst solenoid. When the first solenoid is energized, the inner plungerwill move away from the outlet port to permit fluid to flow through thebuild-up circuit. When the plunger of the first solenoid moves, alatching shaft of a second solenoid is engaged which holds the plungerin the opened position. When the toggle of the breathing rejector isswitched to the OFF position, the second solenoid is energized pullingthe shaft out of engagement and allowing the plunger to be seated,preventing fluid flow through the outlet port. Activation of the demandbreathing regulator by an operator will insure operation conversion ofthe system until a subsequent deactivation of the breathing regulator,providing a fail-safe system uneffective by outside focus.

The flow control valve of the converter is provided with means formanual activation which will override the resiliently biased firstsolenoid, if power is not provided or unavailable. Thus, long standby orconverter tcs t outside the aircraft is possible when electrical poweris unavailable.

It is therefore the object of this invention to provide a fail-safeliquid oxygen conversion to gaseous oxygen system having an activationswitch integrally tied to a breathing regulator device.

It is another object of this invention to provide a fluid flow controlvalve with means to maintain its intended position in a mannerunaffected by outside energy sources uncontrolled by an operator.

It is still a further object of this invention to provide means tomanually activate a flow control valve to operate a liquid to gaseousconversion system.

These and other objects will become apparent to those who read thisspecification and view the drawing.

BRIEF DESCRIPTION OF THE DRAWING The drawing shows a sectional view of aliquid oxygen to gaseous oxygen conversion system connected to abreathing regulator with an enlarged sectional view of a flow controlvalve operationally connected to the ON-OFF toggle of the regulator.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The liquid oxygen togaseous oxygen conversion system 10 shown in the drawing includes adouble walled storage vessel 12 having an inlet port 14 and an outletport 16. The inlet port 14 is externally connected to the outlet portthrough a build-up circuit 20. The inlet port 14 is connected through afill circuit 22 to a liquid oxygen supply adapter 24 and to connectormeans 26 in a supply circuit 28 going to a breathing regulator device30. A pressure responsive interrupting valve 32 is located in thebuild-up circuit 20 downstream from a supply circuit connection 34. Theinterrupting valve 32 will open and close as the pressure in thebuild-up circuit 20 is reduced by withdrawal of gaseous oxygen throughthe breathing regulator 30. Opening and closing the interrupting valvewill assure that the pressure of the gaseous oxygen transmitted to theregulator 30 will remain within a predetermined pressure range.Downstream from the interrupting valve 32 is a flow control valve means36 having an operational signal transmitting line 38 connected to theON-OFF toggle 40 of the breathing regulator 30. The flow control valvemeans 36, upon receiving an operational signal when the toggle 40 ismoved to the ON position, will permit fluid to begin to flow as a liquidthrough port 14. As the liquid oxygen flows through the build-up circuit20, thermal energy converts the liquid to a gas resulting in an increasein internal pressure. The pressure in the build-up circuit will increaseuntil the interrupting valve 32 becomes operational. As long as thetoggle 40 remains in the ON position, the fluid will flow through thecontrol means 36 thereby providing the regulator 30 with pressurizedgaseous oxygen.

Upon moving the toggle 40 to the OFF position, control means 36 willstop the flow in the build-up circuit 20. However, some fluid willremain in the build-up circuit 20 between the flow control valve means36 and the gaseous outlet 16 of the storage vessel. This trapped liquidoxygen will continue to be converted to gaseous oxygen and build up ahead within the build-up circuit 20 and the storage vessel 12. By-passmeans 42, an integral part of the oxygen supply adapter 24, contains apressure opening ball valve 44 which permits excessive pressure toescape harmlessly into the atmosphere. Since liquid oxygen will continueto .be converted to gaseous oxygenthrough the thermal energy penetratingthe storage vessel 12, the ball valve 44 will be operational as long asthe fail-safe system is on standby.

In more particular detail the individual elements of the system could beconstructed as follows to provide a fail-safe operational liquid oxygento gaseous oxygen conversion system.

The liquid storage vessel 12 includes an inner container 46 and an outercontainer 48 separated by an insulating member 50. A capacitance probe52, of a type described in US. Pat. No. 2,848,666, is held against theinterior wall of the inner container 46 by a resiliently biased cap 56adjacent the inlet port 14. The electrical leads 58 of the capacitanceprobe 52 are carried through the gaseous port 16 and out of the storagevesse] 12 through a hermetic opening 60 in the build-up circuit to anelectrical gauge (not shown) for indicating the amount of liquid in thestorage vessel 12.

The supply adapter 24 includes a housing 62 having a supply chamber 64with a spring controlled closure cap 66 overlying an opening 69 to thefill circuit 22. A shaft 68 retained in a bearing wall 71 of the housing62 has a bevelled face 70 extending into a by-pass chamber 74. Thebevelled face 70 is urged against an annular seat 76 surrounding anopening 78 to the atmosphere. An internal passage 80 from the opening 78is connected to the by-pass valve 44.

The interrupting valve 32 includes a housing 82 having a control chamber83 containing a stem 84 with a face 86 on one end and a bellows member88 on the other end. A spring 90 is located inside the bellows member 88and acts on the stem 84 in opposition to a closure spring 92. A wall94'separates the inlet port 96 of the control chamber 83 from the outletport 98. Without pressure in the control chamber 83, the bellows member88 acts in conjunction'with spring 90 to unseat face 86 from the opening100 in wall 94. As the pressure in the control chamber increases, thebellows member 88-will collapse and spring 92 will seat face 86 to closethe flow between the inlet port 96 and the outlet port 98. As thepressure across face 86 drops due to a demand for gaseous oxygen throughthe breathing regulator device 30, spring 90, aided by the force createdby thepressure drop, will overcome spring 92 to again permit fluid toflow.

The flow control valve means 36 includes a housing 102 having a flowchamber with an inlet port 104 and an outlet port 106. A wall 108 havinga passage 111 is located adjacent the outlet port 106. A plunger 110with a beveled end 112 having a shoulder 114 for retaining one end of aresilient member or spring 1 16 is located in an axial line with passage111 and is retained in a bearing wall 118. The plunger 110 extendsthrough the bearing wall 118 into a first solenoid 120. The end 122 ofthe plunger 110 extending into the solenoid 120 has an annular notch 124which receives the end of a holding shaft 126 when the solenoid 120 isenergized and moves the plunger 110 away from passage 111. A

second solenoid 128 surrounds shaft 126, with a resilient member 130being caged between the end 132 of the solenoid and a shoulder 134 onthe shaft to urge the shaft toward the notch 124. Centrally located onthe end of the plunger 110 is a T-shaped cylindrical shaft 136 which issealingly retained in wall 138 of the housing 102. A spring 140 restsagainst the-wall 138 and acts on top portion 142 of the T-shapedcylindrical shaft 136 to aid resilient member 116 in sealing bevelledend 112 against wall 108 surrounding passage 111 to prevent fluid flowtherethrough. A projection solenoid 128 when the toggle 40 is in the OFFposition 164 are not interchanged.

MODE OF OPERATION When it is desired to fill the storage vessel 12 witha liquid, usually oxygen, a supply source is mated with adapter 24. inconnecting the supply source, the shaft 68 is pushed to the rightcompressing spring and thereby communicating outlet 16 with atmospherevia conduit 220, by-pass chamber 74 and opening 78. The supply liquidbeing under pressure unseats cap 66 and flows through fill circuit 22into the fluid inlet 14. Connector means 26 includes a check valve (notshown) which prevents flow at this time to the regulator 30, inaddition, since the toggle 40 is in the OFF position 164, flow throughbuild-up circuit 20 is preventedby the plunger 110 being resilientlyheld against the housing surrounding passage 1 1 1. During the fillprocess liquid flows into inlet port 14 and displaces gas in the innerstorage vessel 46. The displaced gas escapes through gaseous outlet 16,through conduit 220 of the build-up circuit and the by-pass chamber 74to harmlessly escape to the atmosphere. The amount of liquid in thestorage vessel is monitered by the capacitive probe 52 and whensufficiently full, the storage source is disconnected from the supplyadapter 24. Upon disconnecting the supply source, resilient member 75will seat bevelled face 70 against seat 76 and resilient member 67 willseat cap 66 on opening 69 to seal the liquid in the storage vessel 12.

During the passive or standby period, thermal energy will be transferredthrough wall 48, insulating member 50 and wall 46 to cause the liquidoxygen to boil and then be converted to gaseous oxygen. As the pressurein the chamber 13 builds up, this same pressure being present in conduit220 will unseat resiliently held ball valve 44 of means and permit thegaseous oxygen to travel through passage and opening 78 to harmlesslyescape to the atmosphere.

To check the operation of the storage vessel 12 prior to attaching theregulator device 30, T-shaped cylindrical shaft 136 is pushed manuallyuntil spring loaded shaft 126 engages notch 124. Fluid will now bepermitted to flow in build-up circuit 20 until the pressure acting onbellows 88 causes it to collapse thereby permitting spring 92 to seatface 86 and close opening 100. As long as the pressure at the junction34 in the buildup circuit remains constant the pressures across theinterrupting valve 32 will prevent further flow in the build-up circuit20. With any further pressure build-up in circuit 20 fluid is allowed toescape through by-pass valve means 42 to prevent damage to the system.To release the plunger 110 from its held open position, projection 144is pulled to overcome resilient member 130 thereby disengaging the shaft126 from notch 124. Upon disengaging the shaft from the notch, resilientmembers 116 and 140 will again seat plunger 110 on the housing aroundpassage 111 to prevent fluid flow from the inlet port 104 to the outletport 106.

Upon joining the regulators to the supply circuit 28 through connectingmeans 26,. the check valve contained therein is opened permitting liquidoxygen convertible to gaseous oxygen under pressure to be supplied tothe breathing regulator device 30. The intensity of the pressure varieswith the pressure in the buildup circuit created by thermal energy inthe liquid to oxygen conversion. lf fluid flow in the build-up circuithas been interrupted or prevented prior to connecting the breathingregulator device 30, then the initial gaseous oxygen supplied will be ata minimal pressure.

When the operator desires to place the breathing regulator device inoperation, toggle switch 40 is placed in the ON position 162. In the ONposition 162 electrical energy is transmitted through leads 154 156 tothe first solenoid 120. When the coil 121 is energized, the plunger 110becomes magnetized and the mutual action of the field in the solenoid onthe poles created of the ends 112 and 122 of the plunger 110 causetheplunger to move within the solenoid. This moving force becomes zero onlywhen the magnetic centers of the plunger 110 and the solenoid 120coincide. The maximum uniform pull to overcome the resilientlybiasingclosing members 116 and 140 occurs when the end of the plunger122 is located within the bore 123 of the solenoid 120. As the plunger110 moves in the solenoid 120, the bevelled end 122 slides along the endof shaft 126 partially compressing spring 130. When the plunger 110approaches the center of equilibrium with the solenoid 120, shaft 126snaps into groove 124. This latching will occur almost instantaneouslyafter the toggle 40 has been switched to the ON position 162. To preventthe solenoid from heating, a conventional timing device (not shown) willstop the flow of electrical energy to the coil after a predeterminedperiod of time. With plunger. 110 locked open, fluid flow will bepermitted from inlet port 104 to outlet port 106 without hinderance. Asthe flow of liquid oxygen progresses from the liquid port 14 to thegaseous port 16, heat will have converted all the liquid to a gasresulting in an increase in line pressure. When the pressure in thebuild-up circuit reaches a predetermined value, the interrupting valvemeans 32 will close. The pressure across the seat face 86 of theinterrupting valve means 32 will prevent flow in the build-up line untilthe differential is sufficient to overcome the resilient members 92.Through this interrupting valve means, the pressure of the oxygensupplied to the breathing regulator device 30 will remain within apredetermined range.

If electrical power failure should occur, operation of the liquid oxygento gaseous oxygen conversion system will be unaffected since thesolenoid plunger 110 and shaft 126 could be mechanically positioned andremain so until an overt act on the part of the operator repositionsthem. During a power failure if it be desired to return the system to apassive stage, projection 144 could be pulled out to permit theresilient members, 1 16 and to seat plunger 110 and close passage 111 tothereby prevent fluid flow.

With electrical energy available, the operator switches toggle 40 to theOFF position 164 at the end of an active period to stop the flow ofgaseous oxygen through the breathing regulator device 30. Simultaneouslywith the toggle 40 in the OFF position, electrical energy is transmittedthrough leads 158 and to the second solenoid 128 to energize the coil133. When coil 133 is energized, a magnetic flux will occur pullingshaft 126 out of contact with the notch 124 thereby permitting theplunger to be resiliently closed and stop fluid flow in the build-upcircuit 20. After a predetermined period of time, the electrical energywhich is supplied the coil 133 of the second solenoid, is terminated andthe flow control means inactivated.

Once the operator shows a need for oxygen the system is not subject topower failure in the electrical system since the flow of liquid oxygenin the build-up circuit is controlled by the latched solenoid controlvalve 36 tied to the toggle 40 of the breathing regulator device 30.Through the manual override devices 142, for the first solenoid, and144, for the second solenoid, a means is provided to shut the systemdown after a power failure, to activate the system without power and toperform a test on the connector prior to installation in the systemwithout the regulator. ln addition, the number of breathing regulatordevices 30 and 31 can be varied to meet the requirement of the number ofbreathing systems required for the occupants of an airplane, but theoperation of the liquid oxygen connection to gaseous oxygen iscontrolled by the master breathing regulator 30 connected to the flowcontrol valve of the liquid oxygen to gaseous oxygen conversion system.I claim: 1. A fail-safe system for supplying a gas to a regulator in abreathing system in response to a breathing de mand of an operator, saidsystem comprising:

a liquid storage vessel having a liquid port and a gaseous port; a

a pressure build-up circuit connecting said liquid port to said gaseousport, the liquid in said storage vessel being converted from a liquid toa gas by thermal energy upon flowing from said liquid port to saidgaseous port through said build-up circuit;

a supply circuit with a connection connected to said build-up circuitand said regulator, said supply circuit converting said liquid to a gas,said supply circuit delivering said gas to said regulator at a ratenecessary to maintain a physiological level for said operatori pressureresponsive means located in said build-up circuit downstream from saidsupply circuit connection for interrupting the flow of said liquid insaid build-up circuit when the fluid pressure therein caused by theliquid to gas conversion reaches a predetermined value, said pressureresponsive means thereby correspondingly limiting the pressure of thegas transmitted to said regulator through said supply circuit;

by-pass means located in said build-up circuit for venting excessivefluid pressure in said liquid storage vessel to atmosphere; and

control means located in said build-up circuit downstream from saidpressure responsive means, said control means being latched to an openedposition for permitting fluid flow in said build-up circuit to create afluid pressure therein in response to an electrical operational signalbeing communicated from said regulator.

2. The fail-safe system, as'recited in claim 1, wherein said controlmeans includes:

a housing having a chamber located therein with an inlet port connectedto said pressure responsive means and an outlet port connected to saidpressure build-up circuit leading to said gaseous port of the storagevessel;

a plunger retained in a bearing wall in said chamber, said plungerhaving a valve face on'one end and a notch on the other end; firstresilient means secured to said plunger for urging said valve face intosealing engagement with a seat of said housing to prevent fluid flowfrom the inlet port to the outlet port; and

first solenoid means surrounding said plunger having an electricalcircuit connected to an activation section of an operational switchingmeans for said regulator, said first solenoid moving said face away fromsaid seat upon energization by said electrical operational signal.

3. The fail-safe system, as recited in claim 2, wherein said controlmeans further includes:

a shaft retained in a bearing wall adjacent the other end of saidplunger; and

second resilient means secured to said shaft for urging one end of saidshaft toward said plunger, said one end of the shaft engaging the notchend of said plunger to hold the valve face away from the seat upondeactivation of said first solenoid means.

4. The fail-safe system, as recited in claim 3, wherein said controlmeans further includes:

second solenoid means surrounding said shaft having an electricalcircuit connected to a deactivation portion of the switching means ofsaid regulator, said second solenoid means receiving an electricalsignal from a deactivation section of said switch member being operatedupon by an operator, said electrical signal causing said second solenoidmeans to move said shaft away from said plunger permitting said firstresilient means to position said valve face against said seat. 5. Thefail-safe system, as recited in claim 4, wherein said switching means ofsaid regulator includes:

an interconnected circuit between the activation and deactivationsections for transmitting an electrical signal to said control meanscorresponding to an operational signal from an operator to saidregulator. v6. The fail-safe system, as recited in claim 5, wherein saidcontrol means further includes:

override means secured to said plunger for permitting manual movement ofsaid valve face away from said seat causing said shaft to engage saidnotch and thereby allow fluid to flow from the inlet rt to the outletport in said build-up circuit. 7. e fail-safe system, as recited inclaim 6, wherein said control means further includes:

release means secured to said shaft for permitting manual disengagementof said shaft with said notch to allow the valve face of the plunger toseat and prevent fluid flow in said build-up circuit through saidchamber.

8. The fail-safe system, as recited in claim 7, wherein the electricalcircuits for the first and second solenoid includes:

plug-in means for connecting the regulator with the control means havinga lock pin which snaps into a slot to assure proper alignment of thecircuits and the corresponding solenoids.

9. The fail-safe system, as recited in claim 8, wherein said supplycircuit includes:

connector means for opening a check valve upon joining said supplycircuit with said build-up circuit to permit said gas to freely flow tothe regulator.

1. A fail-safe system for supplying a gas to a regulator in a breathingsystem in response to a breathing demand of an operator, said systemcomprising: a liquid storage vessel having a liquid port and a gaseousport; a pressure build-up circuit connecting said liquid port to saidgaseous port, the liquid in said storage vessel being converted from aliquid to a gas by thermal energy upon flowing from said liquid port tosaid gaseous port through said buildup circuit; a supply circuit with aconnection connected to said build-up circuit and said regulator, saidsupply circuit converting said liquid to a gas, said supply circuitdelivering said gas to said regulator at a rate necessary to maintain aphysiological level for said operator; pressure responsive means locatedin said build-up circuit downstream from said supply circuit connectionfor interrupting the flow of said liquid in said build-up circuit whenthe fluid pressure therein caused by the liquid to gas conversionreaches a predetermined value, said pressure responsive means therebycorrespondingly limiting the pressure of the gas transmitted to saidregulator through said supply circuit; by-pass means located in saidbuild-up circuit for venting excessive fluid pressure in said liquidstorage vessel to atmosphere; and control means located in said build-upcircuit downstream from said pressure responsive means, said controlmeans being latched to an opened position for permitting fluid flow insaid build-up circuit to create a fluid pressure therein in response toan electrical operational signal being communicated from said regulator.2. The fail-safe system, as recited in claim 1, wherein said controlmeans includes: a housing having a chamber located therein with an inletport connected to said pressure responsive means and an outlet portconnected to said pressure build-up circuit leading to said gaseous portof the storage vessel; a plunger retained in a bearing wall in saidchamber, said plunger having a valve face on one end and a notch on theother end; first resilient means secured to said plunger for urging saidvalve face into sealing engagement with a seat of said housing toprevent fluid flow from the inlet port to the outlet port; and firstsolenoid means surrounding said plunger having an electrical circuitconnected to an activation section of an operational switching means forsaid regulator, said first solenoid moving said face away from said seatupon energization by said electrical operational signal.
 3. Thefail-safe system, as recited in claim 2, wherein said control meansfurther includes: a shaft retained in a bearing wall adjacent the otherend of said plunger; and second resilient means secured to said shaftfor urging one end of said shaft toward said plunger, said one end ofthe shaft engaging the notch end of said plunger to hold the valve faceaway from the seat upon deactivation of said first solenoid means. 4.The Fail-safe system, as recited in claim 3, wherein said control meansfurther includes: second solenoid means surrounding said shaft having anelectrical circuit connected to a deactivation portion of the switchingmeans of said regulator, said second solenoid means receiving anelectrical signal from a deactivation section of said switch memberbeing operated upon by an operator, said electrical signal causing saidsecond solenoid means to move said shaft away from said plungerpermitting said first resilient means to position said valve faceagainst said seat.
 5. The fail-safe system, as recited in claim 4,wherein said switching means of said regulator includes: aninterconnected circuit between the activation and deactivation sectionsfor transmitting an electrical signal to said control meanscorresponding to an operational signal from an operator to saidregulator.
 6. The fail-safe system, as recited in claim 5, wherein saidcontrol means further includes: override means secured to said plungerfor permitting manual movement of said valve face away from said seatcausing said shaft to engage said notch and thereby allow fluid to flowfrom the inlet port to the outlet port in said build-up circuit.
 7. Thefail-safe system, as recited in claim 6, wherein said control meansfurther includes: release means secured to said shaft for permittingmanual disengagement of said shaft with said notch to allow the valveface of the plunger to seat and prevent fluid flow in said build-upcircuit through said chamber.
 8. The fail-safe system, as recited inclaim 7, wherein the electrical circuits for the first and secondsolenoid includes: plug-in means for connecting the regulator with thecontrol means having a lock pin which snaps into a slot to assure properalignment of the circuits and the corresponding solenoids.
 9. Thefail-safe system, as recited in claim 8, wherein said supply circuitincludes: connector means for opening a check valve upon joining saidsupply circuit with said build-up circuit to permit said gas to freelyflow to the regulator.